Grinding machine



June 28, 1938. A. scRNENE GMNDING MACHINE Y Filed Jan. l5, 1937 yit 'Patented June 28, 1938 alzarsi ,d narran srares PATENT ermee ApplicationJanuary 15, 1937, Serial No. 120,708 In Great Britain February 14, 1936(Cl. 51-103i 3 @Balma This 'invention `is for improvements in connectionwith g'rinding machines of the kind in which the work-piece is supportedbetween centresand is mechanically rotated in pressure con- 5 tact witha rotating grinding wheel.

The object is to provide, in a grinding machine of this kind, a means ofgenerating screwthreads or other helical surfaces of a high degree ofaccuracy and finish, or of correcting such surfaces after generation bya less accurate method or after a hardening or like operation, and ofthereby facilitating the continuous output necessary in the repetitiongrinding of screwthreaded bolts, studs, and the like.

According to the present invention, in a grinding machine of the kindreferred to, the centred work-piece is correctly aligned in relation toannular serrations cn the grinding wheel by means of .a universallyadjustable control finger which work-piece orof a master formerrotatable between centres in axial alignment with the workpiece centres,said control finger. serving also to traverse the rotating work-pieceacross the face of the grinding wheel at a rate governed by the speed ofrotation of the work-piece and by the pitch of said helical surface.

In order that the inventionV may be clearly understood and readilycarried into practice, reference may be had to the appended explanatorydrawing, in which: Y

Figure l is a front elevation, and Figure 2 is a plan, of such parts ofa grinding machine as are necessary to illustrate the invention.

Figure 3 is asimilar plan illustrating a modified form of the invention.

Figure a is an end elevation of a after referred to.

Similar letters refer to similar parts throughout the several views.

detail herein- In a convenient method of carrying the iinvention intoeffect,V as illustrated in ilgures` 1 and 2 and as applied by way ofexample to a grinding machine of the kind referred to for the correctionof screw-threads initially formed upon bolts, studs, and the like by arolling or other operation, the work-piece a is mounted between a pairof centres b of which one is adjustable as at c for varying lengths ofwork and is springloaded as at d so as to support the work-piece a butleave it free to rotate, the centres being mounted in anti-frictionbearings. The headstocks e carrying the centres b are mounted on a tablewhich slides freely on anti-friction bearings g on the bed h of themachine in the contacts with the helical surface either of the directionof the axis of the work-piece a. At right angles to the slide table f isarranged another slide carrying the rotatable grinding wheel whichtherefore is capable of movement at right angles to the axis of theworkpiece a, this movement determining the-size of the work-piece adiametrically. The face of the grinding wheel i is formed with annularserrati'ons disposed at right angles to the axis of the work-piece avand adapted to produce the desired form upon the work-piece a, which isrotated by a backing wheel y' mounted either on a pivoted arm or on aslide so that it can be spring-loaded or otherwise urged towards thework-piece a so as to drive it by frictional contact. The backing Wheely is geared to an electric motor or other source of power so as tovbedriven at a speed which imparts a suitable peripheral velocity to thework-piece a. Attached to the Agrinding wheel head is an arm k carryinga control inger l which abuts radially on the top of therwork-piece athis iinger l being springloaded and being universally adjustable inrelation to the ,work-piece a, that is to say, it has a fine micrometeradjustment in directions parallel to the axis of the grinding wheel i,and is also adjustable in two planes at right angles to the grindingwheel axis to suit various diameters of work-piece and grinding wheel,the control finger l being also rotationaily adjustable in its bearing.

In the operation of this form of the machine, the grinding wheel Ai isfirst withdrawn either manually or automatically, taking with it thecontrol finger l. The work-piece a is then inserted between the centresb, and the backing wheel 9 is brought into contact-so as to rotate thework-piece. The grinding wheel i is then brought upto the work, thecontrol finger l conjtacting with the work-piece a and aligning it withthe serrations on the wheel which is now in its grinding Iposition. Itwill be seen that lution, whilst any longer piece will revolve until thewhole of its threaded surface has passed the wheel i or the control ngeri.

t of the grinding wheel i, the grinding wheel head may be stationary,and the whole of the ,other mechanism be arranged to slide in adirection at right angles to the axis of the work-piece a. Moreover thecomplete slide unit may be dupli- -cated so vas to provide a series ofloading and operating stations, the work being loaded at one stationwhilst it is operated on at another, and the change of stations beingeiiected either manually or automatically.

In another method of carrying the invention into eect, as illustrated inFigure 3 and as applied by way of example to a grinding machine of thekind referred to for the generation and finishing of screw-threads uponbolts, studs, and the like, the work-piece blank a is mounted betweenone pair of centres b, and a master former m is similarly mountedbetween another pair of centres bl, the two pairs of centres b and b1being disposed in axial alignment, and both the 'work-piece a and theformer m being of the same diameter. The work-piece a and the former 1p.are rotated by separate backing wheels fand j* which are independentlyurged forward to provide a frictional drive at the same speed both forthe work-piece a and for the former m. The face of the grinding wheel iis formed with annular serrations disposed at right angles'to the axisof the work-piece a and adapted to produce the desired form on thework-piece a. A universally adjustable control finger l ashereinbefore'described is attached to the grinding wheel head by acarrier arm Ic so as to be adapted for engagement with the screw-threadon the master former m.

In the operation of this modified form of the machine. the `machine isloaded as herelnbefore described with reference to the rst form of theinvention, and it will be seen that as the control finger l is inengagement with the master former m .rotating at the same speed as thework-piece a, this causes the workepiece a to travel across the face ofthe grinding wheel i, thus generating ,the desired screw-thread andthereby reproducing the form of the master m on the'blank o, one or`more revolutions being required to complete the piece. When-it isrequired to pass the work hrough the machine more than once, for exampleor the production of a highly accurate finish, a

second control finger l1 may be provided, this4 operating in associationwith the screw-thread table both in relation to the primary controleratedl on the work-piece a and being ader land to the 'serrations onthe grinding wheel i, so as to assist in re-positioning the workpiece aon the grinding wheel i for the secondary grinding operation.

It will be appreciated that work with aninter.

rupted surface can betground. provided that a continuous surface isavailable at some part or other so that the backing wheel i can rotatethe work-piece. For example, screwing taps may'be treated by arrangingthe backing-wheel 1 against the shank of the tap and by adjusting thediameter of the master former m to suit. For this type of work, when asecond pass is required, the second control finger ll may be extendedlaterally as shown in Figure 4 so as to bridge the flutes cix of thework-piece a and engage two lands at the same time.

I claim: 1. In a grinding machine of the kind described.

- for the correction of screw-threads and other helical surfaces, thecombination of an annularly serrated grinding wheel, a pair of centresadapted to support the work-piece, a. backing wheel adapted to rotatethe work-piece between said centres in pressure contact with thegrinding wheel, and a universally adjustable control finger adapted toabut on the helical surface of the work-piece, said finger ensuring thatthe screwthreads on the centred work-piece are correctly aligned inrelation to the annular serrations on the grinding wheel, and servingalso to traverse therotating work-piece across the face of the grindingwheel at a rate governed by the speed of rotation of the work-piece andby the pitch of the helical surface.

2. In a grinding machine of the kind described, for the generation ofscrew-threads and other helical surfaces, the combinationof an annularlyserrated grinding wheel, a pair of centres adapted -to support thework-piece, a backing wheel 'in axial alignment with the work-piece, abacking wheel adapted to rotate the master former between said centresat the same speed as the workpiece, and a universally adjustable controlnger adapted to abut on the helical surface of the master former, saidnger ensuring that the centred work-piece is correctly aligned inrelation to the annular serrations on the grinding wheel,A and servingalso to traverse the rotating work-piece across the face of the grindingwheel at a rate governed by the speed of rotation of the master former,and by the pitch of the helical surface thereon. v

3. In a grinding machine of the kind described, for the generation ofscrew-threads and other helical surfaces, the combination of anannularly serrated grinding wheel, a pair of centres adapted ,to supportthe work-piece, a backing wheel adapted to rotate the work-piece betweensaid centres in pressure contact with the grinding wheel, `a helicallysurfaced master former, a pair of centres' adapted to support saidmaster former in axial alignment with the work-piece, a backing wheeladapted to rotate the master former between said centres at the samespeed as the workpiece, a universally adjustable control finger adaptedto abut on the helical surface of the master former. and a secondcontrol finger adapted to abut on the helical surface generated on thework-piece. the first-mentioned control linger ensuring that the centredwork-piece is i correctly aligned in relation to the annular serrationson the grinding wheel, and serving also required.

, sRTHUR scarvENER.

